1. Field of the Invention
The invention relates to a receiving part for receiving a rod for coupling the rod to a bone anchoring element, and a bone anchoring device with such a receiving part. The receiving part includes a receiving part body with a rod receiving portion and a head receiving portion for receiving the head of the bone anchoring element and a locking ring for locking the head in the head receiving portion. The head can be clamped by compressing a plurality of flexible wall sections with the locking ring, where the clamping force is generated in a wall section at a circumferentially distinct pressure area.
2. Description of Related Art
U.S. Pat. No. 5,733,285 describes a polyaxial colletted locking mechanism for use with an orthopaedic apparatus including a screw having a curvate head and a coupling element. The coupling element has a tapered and colletted portion having an interior chamber in which the curvate head is initially polyaxially disposed. A locking collar is disposed around the tapered and colletted portion such that translation thereof in the direction of the expanding taper causes the interior volume to contract onto the curvate head and lock it therein.
WO 2007/038350 A2 discloses an apparatus for connecting a bone anchor to a support rod, the apparatus including a connector body and a cap. The connector body has a socket for insertion, angulation and removal of a bone anchor. A sleeve is provided which is configured to fit over the connector body for locking the bone anchor in the socket.